Ignition apparatus



y 1943- J. R. FREI ETAL. 2,445,57

IGNITION APPARATUS Filed June 24, 1944 2 Sheets-Sheet l Fig. 3

1+1 INVENTORS.

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H T TORNEY July 20, 1948. J. R. FREl ET AL IGNITION APPARATUS 2 Sheets-Sheet 2 Filed June 24, 1944 BOOSTER COILS INVENTORS.

j flwcm JM A TTOR/Vf y Patented July 20, 1948 IGNITION APPARATUS Jakob R. Frei, Sidney, and Rolland M. Purdy, Bainbridge, N. Y., assignors to Bendix Aviation Corporation, New York, N. Y., a corporation of Delaware Application June 24, 1944, Serial No. 541,989

12 Claims.

r .This invention relates to ignition apparatus for the ignition system of an internal combustion engine, or the like, and mor particularly to means for controlling electrical circuits and distributing electrical current impulses to a plurality of circuits.

One of the objects of the present invention is to provide novel apparatus for controlling the flow of electrical current in a plurality of connected circuits in the ignition system of an internal combustion engine.

Another object of the invention is to provide novel unitary apparatus for distributing electrical current at relatively low voltage from a plurality of sources to a larger number of branch circuits in timed sequence.

Still another object is to provide a light, compact device which is sturdy and reliable for distributing electrical current at relatively low voltage from one or more sources of electrical current to the spark plugs in the cylinders of a multicylinder engine.

A further object is to provide novel simplified apparatus for controlling the flow and distribution of electrical current from a plurality of current generating means to the spark-plugs of an engine.

A still further object is to provide apparatus of the above character wherein the rotating parts are small and light and may be driven at relatively low speeds even in an engine having a large number of cylinders and requiring the generation of a large number of sparks during short intervals of time.

Another object is to provide novel means for mounting a spring-pressed current carrying brush of carbon or like material in a rotating or other part whereby the movement of the brush by the spring is limited.

Another object is to provide a novel simplified apparatus of the above character wherei the parts may be readily assembled and disassembled for inspection, repair and adjustment with utmost facility and wherein the surrounding casing may be readily removed to permit inspection and adjustment without disturbing the operating parts.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawingsare for the purpose of i1.- lustration only and are not intended as a. definition of the limits of the invention, reference for this latter purpose being had primarily to appended claims.

In the drawings, wherein like reference char-L acters refer to like parts throughout the several views,

Fig. 1 is a side elevation, mostly in section and with parts broken away and parts removed in the interest of clarity, showing one form of apparatus embodying the invention, the section being taken substantially on lines ll of Figs. 3 to 7,v

inclusive;

Fig. 2 is a detail sectional view taken substantially on lines 22 of Figs. 4 to'l, inclusive, and approximately on lines 2--2 of Figs. 1 and 3 with the distributor rotor shown in full;

Fig. 3 is a transverse sectional view taken substantially on line '33 of Fig. land showing a representative portion of the circuit breaker an enlarged scale taken at nearly right angles to.

each other and showing novel means for mounting the distributor brushes in the distributor rotor; and,

Fig. 10 is a wiring diagram illustrating the use of the device in an ignition system.

The single embodiment of the invention illustrated in the accompanying drawings, by way of example, is adapted for use in the ignition system of an 18-cylinder four-stroke cycle internal combustion engine. It may, for instance, be employed for distributing alternate current impulses from two sources of electrical energy to a set of spark plugs in the cylinders of a double row radial type engine wherein the cylinders of one row are staggered angularly with respect to the cylinders readily available for inspection and repair with out in any way disturbing the operating parts or the relative adjustment thereof. In the form the shown, the casing comprises a main or supporting structure H], a central open-ended tubular member H slidably fitted around axially extending parts of the support l and a distributor and cable housing l2 fitted with a cover l3 and having a cable outlet l4. Central housing member I! serves as a spacer between parts I0 and 12 which are removably secured together by means of a plurality of bolts l5. Housing member l0 may be secured by means of bolts Hi to the casing of an engine or to an adaptor l! which is in turn secured to the engine casing by means of bolts l8.

To provide for limited angular adjustment of the device when mounting the same on an engine, bolts I6 may extend through elongated arcuate slots 19 (Fig. 3) in casing member ID. Bolts l6 are preferably permanently mounted in the engine casing or adaptor ll and casing member I0 is held in position by nuts 20. If desired, adaptor I! may take the form of a housing for an automatic advance-retard mechanism or variable coupling which may be employed for coupling the present device to an engine.

A rotatable shaft 2| concentric with the arcuate slots i9 is mounted in spaced roller bearings 22, 23 provided in the framework of easing member Ill. The left end of said shaft as viewed in Fig. 1 extends through adaptor I1 and is provided with a suitable gear or splined member 24 for driving engagement with a part of the engine (not shown). Drive member 24 is preferably adjustably coupled to shaft 2i by coupling means 25 of the character disclosed in Spengler U. S. Patent No. 2,266,283 so that small angular adjustments of a permanent nature may be made for ignition timing purposes. An oil seal 26 of any suitable time such as a Gite seal, for example, may be mounted around shaft 2| in the transverse end wall 21 of housing member In for preventing oil from entering the circuit breaker chamber 28 from the engine crank case or gear housing on which the apparatus is mounted. If desired, shaft 21 may have the magnetic or flux distributing rotor of a magneto generator mounted thereon and enclosed by a suitable extension of casing member ll.

In order to create periodic surges of electrical current at a suitable voltage in the spark plug circuits of an internal combustion engine for a purpose to appear hereafter, two or more circuit breaker earns 29 and 30 are keyed or otherwise suitably secured on shaft 2| for rotation therewith between bearings 22 and 23. Each of said cams as shown is of the compensated type provided with nine lobes suitably spaced for controlling the supply of electrical energy to the spark plugs of nine radially disposed cylinders in a manner well understood in the art. Two circuit breakers MI and BI which may be of the typ shown. in Shoemaker et al. Patent No. 1,866,492 are adjustably mounted on an axially extending support 32 01 housing member ID for actuation to open position by cam 2 9.. Two circuit breakers M2 and B2 of the same type are mounted in the same manner for actuation by cam 30, said cam and circuit breakers being so mounted that the points or contacts of main circuit breakers Mi and M2 will be alternately operated in timed sequence and the points or contacts of booster circuit breakers BI and B2 will be similarly operated but in retarded relation with respect to the operation of the corresponding main circuit breakers. One set of said circuit breakers is illustrated in Fig. 3 and the other set, is shown only diagrammati'cally in Fig. 10,but both sets may b sub,-

stantially identical. Each of the main circuit breakers has one of its points or contacts grounded through the casing heretofore described and the other contact connected with a source of electrical energy, such as a magneto generator having an induction coil operatively associated in a well known manner with a permanent magnet and a magnetic flux distributing rotor. Each of the booster breakers has both of its points or separable contact insulated from ground and con nected in the ignition circuit in a manner to ap pear hereafter. As shown, an insulating block 3| (Fig. 3) is employed between each booster breaker and frame member 32 which is part of casing member l0.

Tubular casing member ll surrounds the circuit breakers and in the bottom thereof a pair of condensers 33 and 34 are suitably mounted. In the illustrated embodiment both condensers are supported by sheet metal brackets 35 secured by means of said screws to axially extending portions of frame ID in the manner best shown in Fig. 3. Each condenser has one side thereof grounded through its casing and housing member In and the other side thereof connected to the ungrounded contact or point of one of the main circuit breakers, as shown in Fig. 10.

Secured to the right hand end of frame l0, as view-ed in the drawings, and constituting a part of the novel ignition distributor comprehended by the present invention is an insulating plate 36. For a purpose to appear more fully hereafter, the studs 3! which secure plate 36 in position extend through elongated arcuate slots 33 in said plate and, hence, permit limited angular adjustment of the plate around the axis of rotation of shaft 2| Partially embedded in insulating plate 36 and projecting from one face thereof are two concentric metallic rings 39 and 40. Said rings are connected by inserts 4| and 42', respectively, to terminals 43 and 44, respectively, which are embedded in and extend through plate 36 near the periphery thereof. The ends of terminals 43 and 44 within circuit breaker chamber 28 are connected with the insulated contacts of the main circuit breakers MI and M2, respectively, by suitable conductors shown only in Fig. 10. Each of two additional terminals 45 and 46 having the same construction as or being similar in. construction to terminal 43 is connected to one contact of each of the booster circuit breakers BI and B2. The other contact of each of the booster circuit breakers iselectrically connected to the insulated side of a main circuit breaker. These connections are clearly shown in Fig. 10.

Facing plate 36 and spaced axially therefrom is a second insulating plate or distributor block 41 which extends transversely across the interior of housing member l2 and is mounted in the latter by means of stud bolts 48, only one of which is shown. Embedded in plate or block 41 and projecting from the left face thereof, as viewed in Figs. 1 and 2, are two series or sets of arcuate contacts 49 and 50 arranged in concentric circles about the axis of rotation of shaft 21. Each contact 43 of the inner circle is in radial alignment with a contact 551 of the outer circle (Fig. 6) and each of the contacts 49 and 50 is connected to or integral with a terminal post 5i that extends through block 41 to the opposite face thereof. In the illustrated embodiment there are nine contacts in each circular series. Terminal posts 5| may be counterbored to receive a terminal screw 52 for connecting a conductor or cable 53 to each. of saidposts. These cables conduct electrical energy t-o transformer coils 54, the secondary windings of which may be connected to spark plugs 5'5 in the engine cylinder (Fig.

Embedded in block 41 near the periphery thereof and opposite terminals 43, 44, and 46 in plate 36 are corresponding terminals 43a, 44a, 45a, and 46a, respectively. Means are provided for automatically electrically connecting the last-mentioned terminals in block 41 to the respective terminalsin plate 36 when cover or housing member l2, I3 is moved into assembled position. In the form shown, said means in each instance comprises a relatively rigid bracket-like member 56 which has a coil spring 51 or the like secured to one end thereof for yieldable engagement with a terminal in plate 36 while the other end of said member .threadedly engages a screw 58 (Fig. 2). Said. screw extends through the hollow terminal embedded in block 41 and is adapted to hold an incoming conductor in electrical engagement with the, terminal and, hence, with connector 56, 51.

Shaft 2| extends freely through a central opening in plate 36 and has'a rotor 59, commonly known, as a distributor finger, removably mounted thereon for rotation therewith, such as by means of a'keyl 66 and a nut 6| threaded onto the end of the shaft. Said rotor or finger consists primarily of an elongated block of insulated material equipped with novel means adjacent each end thereof for continuously picking up electrical current from rings 39 and 48 and conducting the same to terminals or contacts 49 and 58, respectively, on distributor block 41. Current picked up from the outer ring 39 is conducted to the inner ring or series of contacts 49 by a pair of carbon or like brushes 62 and 63 slidably mounted in recesses in finger 59 and projecting from opposite faces thereof at different radial distances from the axis of rotation of shaft 21.

The inner end of each brush has a coil spring 64 attached thereto and the free ends of the two springs are mechanically and electrically connected by a metallic strip 65 embedded in the insulationof finger 59. The springs 64 are of such length as to press brushes 62, 63 against ring 39 and contacts 49, respectively, when the parts are in assembled relation as shown in Figs. 1 and 2. Current picked up from inner ring 48 is conducted to the outer ring of contacts 58 by a pair of brushes 66 and 61 mounted in the other end of rotor 59 and connected together in the same manner as brushes 62 and 63.

Novel means are provided in combination with each of the brushes 62, 63, 66 and 61 and its associated spring for limiting the extension of the latter and thereby preventing the same from pushing the brush completely out of its recess in finger 59 when the latter is removed from shaft 2| or when housing section l2, l3 and, hence, block 41 is detached from the remainder of the housing. As shown, said means consists of two interlocked loops of wire 68 and 69 (Figs. 8 and 9). One endof loop 68 has at least one coil or turn 18 which engages one end of spring 64. The remainder of wire 68 forms a loop or bite within spring 64 and the end thereof projects outwardly through a washer 1| and conducting member 65 and is bent over and soldered in place as indicated in Fig. 9. The other loop 69 interlocks with loop 68 within spring 64 and the turned-in ends 64 thereof have interlocking engagement with a plate-like element 12 having a circumference approximately equal to the outside circumference of spring 64 and slotted to receive wire 64. Element "12 is soldered or otherwise suitably secured,

preferably in a recess 13, in the metal plated end of brush 62. The combined length of loops 68 and 69 is such as to prevent spring 64 from moving the carbon brush out of its recess in finger 59 but is nevertheless sufficient to permit the spring to press the brush firmly against the ring or contacts which it is intended to slidably engage.

By reason of the novel construction of the above-described apparatus, it is an easy matter to properly assemble the parts and to time the device to an engine during the installation thereof on the engine. For this purpose a timing mark 14 is placed on rotor 59 (Fig. 2) and four angularly spaced radial marks 15, 16, 11 and 18 (Fig. 5) are placed on the right hand face of plate or disc 36, as viewed in Fig. 1. These radial marks represent the proper position of the rotor mark 14 when the circuit breakers Ml, Bl, M2 and B2, respectively, are initially opened for firing the plugs in selected cylinders of the engine and are employed in a novel manner to properly assemble the apparatus and correct for the angular manufacturing tolerances allowed in connection with the positioning of the keyways on the cams and distributor rotor, and shaft 2i, the positioning of the holes for bolts 31 and the like. Thus, in the process of assembly, circuit breaker Ml", for example, is first adjusted so that it will be held in open position for a predetermined angular rotation of shaft 2| by the lobe of cam 29 which circles the firing in a preselected cylinder such as the number 1 cylinder of the engine. Then with the shaft and rotor 59 in the position at which the opening of circuit breaker MI is initiated, plate 36 is angularly adjusted to bring the marks 14 and 15 in alignment, in which position said plate is firmly secured to housing member ID by bolts 31. The remainder of the circuit breakers Bl, M2 and B2 are individually adjusted on supporting arm 32 so that the contacts thereof will start opening when rotor mark 14 is in alignment with marks 16, 11 and 18, respectively.

Having thus assembled the device and with the piston in the number 1 cylinder of the engine (or other pre-selected cylinder) in its firing position, the member 24 is moved into mesh with the engine driving member while the mark 14 on rotor 59 is in alignment with mark 15 on plate 36 and slots 19 are in alignment with bolts Hi. This meshing and alignment may be effected through proper adjustments permitted by the adjustable coupling 25. The main circuit breaker Ml which is connected to control the firing of the spark plug in the number 1 cylinder (or other preselected cylinder) will then be opened by its cam 29 everysecond time the piston in said cylinder reaches its firing position. The other circuit breakers have likewise been adjusted by the use of marks 16, 11 and 18 so that circuit breakers M2, BI and B2 will be opened at proper intervals and in proper timed relation with the engine. The proper angular positions for marks 16, 11 and 18 with respect to mark 14 may be readily calculated by taking into consideration the angular distances between lobes on the circuit breaker cams and between cam followers of circuit breakers operated by the same cam, the angular rotation of the engine between the firing of pre-selected successively firing spark plugs, and the positions of the cams relative to each other. It may be pointed out that both plate 36 and block 41 are provided with location notches 19 and 88, respectively (Figs. 1, 4 and 5), which mesh with suitable pins 91 and 92 or the like 7 in casing member H to avoid improper installation of the block. 41 in the casing member i2 and of said casing member on casing member I8.

The functioning of the above-described apparatus may best be understood by considering its operation in a complete ignition system, as shown diagrammatically in Fig. 10. In starting the engine on which the system is mounted, energy may be supplied by a battery 8| or other suitable source through a starter switch 82 to a pair of booster or buzzer coils 83 of any suitable known construction which periodically interrupts the direct current from battery ill. The interrupted current from one of the booster coils, for example, flows through a lead 84 to one side of booster breaker Bl. This lead extends into the apparatus of Fig. 1 through opening l4 and includes the terminal 45a, a connector 55, 51 and terminal 45 in plate 36. When both breakers BI and MI, which are operated by cam 29, are in closed position, current flows through the booster breaker Bi and the main breaker Ml to ground. When, however, breaker BI is in closed position and breaker M I is in open position the current flows through leads 85 and 86 to outer ring 39. It will be seen that the connection 85, 86 of Fig. 10 includes the terminal 43 and insert 41 embedded in distributor plate 35. From ring 39 this booster current flows through brushes 52 and 63' in rotor 59 to an arcuate contact 49. on block 41 and thence through a terminal post and a lead 53 to a transformer coil 54, the secondary winding of which is operatively connected to a spark plug 55 as heretofore described. The flow of interrupted current through the primary wind-- ing of the coil 54 induces current impulses in the secondary winding of the coil at sufficiently high voltage to produce a shower of sparks across the gap of the spark plug. Current from the other of the pair of booster coils is conducted through booster breaker B2, ring 40, brushes 66, 61, and distributor contacts 50 in a similar manner to other spark plugs and will not be described in detail. This latter circuit, of course, includes their terminals 46a, 46' and 44' and insert 42 in that order.

When the engine is started and is running at a sufficiently high speed, current may be furnished by one or more engine driven magneto-generators, the induction coils of which are illustrated at 81 and 88 in Fig. 10. The ungrounded or high potential end of coil 81 is connected by means of leads S9 and 85 to main circuit breaker MI. The lead 89 of Fig. enters the device of Fig. 1 through inlet i4 and includes terminal 43a, 3. connector 56, 51 and terminal 43 in plate 36. Terminal 43 is connected to the insulated. side of circuit breaker MI by lead 85.. Coil 81 is also connected to ring 39 of the distributor by leads 89 and 86, the latter being represented by insert 4i in Fig. 1. When circuit breaker MI is closed, the current flows through the breaker because this circuit contains less resistance than the parallel connected circuit of which lead 86' is a part. When the current flow is near its maximum value, main circuit breaker MI is opened by cam 29. This results in a sudden surge of current through the circuit including lead 89, lea-c186,. ring 39, brushes 62 and E3, a contact 48, a lead 53, and the primary winding of a transformer coil 54. This sudden surge of current through said primary winding results primarily from self in duction in coil 8! and is effective to induce a relatively high voltage in the secondary winding of the transformer coil and, hence, produce a spark across the gap of a spark plug 55. The current impulses produced in winding 88 alternate with those produced in winding 81 and the flow thereof is controlled in a similar manner by main circuit breaker M2 and that portion of the distributor mechanism comprising ring 40, brushes 66, 61 and contacts 50 in distributor block 41.

There is thus provided a novel, simplified ignition unit for timing the electrical impulses or sparks in the ignition system of an engine and for distributing the same in proper timed relation to the spark lugs, said unit being so constructed that the rotating parts thereof may be driven at half engine speed- The novel construction of the unit facilitates the internal timing adjustments thereof and also the timing of the unit to the engine on which it is mounted. Additionally, the novel unit comprehended is adapted to be housed in such a manner as to make it easy to inspect the operating parts without disturbing said parts or their relationship to one another. Said unit is also compact and durable as well as reliable and eflicient during operation. Novel means for positioning the brushes of a distributor finger in a simple and reliable manner to prevent damage thereof by careless mechanics or otherwise are also provided.

Although only a single embodiment of the invention has been illustrated, it is to be expressly understood that the same is not limited to this particular structure. Various alternative embodiments have been hereinbefore mentioned and many other variations, especially in the design and arrangement of parts illustrated, may be made without departing from the spirit and scope of the invention as it will now be understood by those skilled in the art. For a definition of the limits of the invention, reference is had primarily to the appended claims.

What is claimed is:

1. In ignition apparatus of the character described, a casing, a rotatable shaft journalled in said casing, two circuit breaker means each comprising a cam mounted on said shaft for rotation therewith and separable contact points adjustably mounted on said casing for periodic operation by said cams, a distributor finger mounted on said shaft for rotation therewith, an insulating plate mounted on one side of said finger in said casing for angular adjustment relative to the latter, two concentric metallic rings mounted on said block in concentric relation with said shaft, a cover removably mounted on said casing, an insulating block mounted in said cover on the other side of said finger, two concentric circles of angularly spaced metallic contacts on the face of said block adjacent said finger, a terminal post for each of said contacts extending through said block for connection with an outgoing cable, a pair of spring-pressed brushes carried by said finger at one side of said shaft for conducting current from the outermost of said metallic rings to the contacts of the innermost of said circles of contacts, and a pair of spring-pressed brushes carried by said finger at the other side of said shaft for conducting electrical current from the innermost of said rings to the outermost of said circles of contacts.

2. In ignition apparatus of the class described, a supporting member, a shaft rotatably journalled in said member, circuit breaker means including at least one pair of separable contact points mounted on said supporting member and cam means on said shaft for periodically separating said points, a tubular casing member slidably mounted on said supporting member around said circuit breaker means, a cup-shaped casing member engaging one end of said tubular casing member, means for removably securing said cupshaped member to said supporting member, and current distributing means enclosed by said cupshaped casing member including a current distributing rotor mounted on said shaft and a plurality of circularly arranged contacts mounted in and insulated from said cup-shaped member.

3. In an ignition distributor, a supporting member, a shaft rotatably joumalled on said member, an insulating plate mounted onsaid member around said shaft, a conducting ring on said plate concentric with the axis of rotation of said shaft, a terminal on said plate electrically connected with said ring, a cup-shaped casing member removably mounted on said supporting member, a distributor block mounted in said casing member, a plurality of contacts on said block circularly disposed around the axis of rotation of said shaft, a terminal in said block opposite said first-named terminal, means for automatically electrically connecting said terminals when said casing member is secured in place on said supporting member, and means rotatable with said shaft for conducting electrical current from said ring to said contacts.

4. In an ignition distributor, a casing member having axially extending supporting means, a shaft rotatably journalled in said supporting means, at least one circuit breaker mounted on said supporting means, cam means on said shaft for actuating said circuit breaker, a tubular casing member slidably mounted on said supporting means and surrounding said circuit breaker, a cup-shaped casing member engaging the end of said tubular casing member and removably secured to said first-named casing member, and current distributing means enclosed by said cupshaped casing member including at least one current conducting ring mounted on said supporting means, a plurality of circularly disposed contacts mounted in and insulated from said cup-shaped casing member and a current distributing rotor for conducting current from said ring to said contacts.

'5. In an ignition distributor, a supporting member, a shaft rotatably journalled in said member, 7

a conducting ring mounted on and insulated from said supporting member in concentric relation with the axis of rotation of said shaft, a plurality of circularly arranged contacts removably supported by and insulated from said supporting member, a current distributing rotor mounted on said shaft between said ring and said contacts, a spring pressed brush on said rotor engaging said ring, a spring-pressed brush on said rotor for successively engaging said contacts, and means electrically connecting said brushes.

6. In an ignition distributor, a supporting member, a shaft rotatably journalled in said member, an insulating plate mounted on said member around said shaft, a conducting ring on said plate concentric with the axis of rotation of said shaft, a terminal on said plate electrically connected with said ring, a distributor block removably supported by said supporting member, a plurality of contacts on said block circularly disposed around the axis of rotation of said shaft, a terminal in said block, means for automatically electrically connecting said terminals when said block is secured in place on said supporting meml0 ber, a rotor on said shaft between said block and plate, and means including spring-pressed brushes on said rotor for conducting electrical current from said ring to said contacts during rotation of the rotor.

'7. In an ignition distributor having a rotatable current distributing assembly comprising an insulating block having axially-extending radiallyspaced recesses in opposite faces thereof, a conducting brush, such as a carbon brush, slidably mounted in .eachof said recesses, one of said rushes projecting beyond one face of said block and the other of said brushes projecting beyond the other face of said block, and resilient means in each of' said recesses tending to urge said brushes out of said recesses, of means embedded in said block and comprising an electrically conductive metallic strip having portions extending across said recesses for mechanically supporting said resilient means and for electrically connecting said brushes to each other.

8. In an ignition distributor having a rotatable current distributing means comprising a block of insulating material, a conducting brush, such as a carbon brush, slidably mounted in a recess in said block, and a coil spring secured to said block and brush for urging said brush outwardly in said recess, of a pair of relatively stiff interlocking loops engaging opposite ends of said spring for limiting the maximum extension thereof and the outward movement of said brush.

9. In an ignition distributor, a current distributing rotor, an insulating plate surrounding the axis of rotation of said rotor at one side thereof, at least two concentric conducting rings on said plate, an insulating block on the other side of said rotor, at least two concentric rings of angularly spaced contacts on said block, means on said rotor at one side of said axis for conducting current from one of said conducting rings to one of said rings of contacts, and means on said rotor at the other side of said axis for conducting current from the other of said conducting rings to the other of said rings of contacts.

10. In apparatus of the class described, a casing member, a rotatable shaft journalled in said member, at least one circuit breaker adjustably mounted on said member, a cam keyed to said shaft for rotation therewith for periodically separating the contact points of said circuit breaker during a predetermined angular rotation of said shaft, a current distributing rotor mounted on said shaft for rotation therewith, a plate mounted on said casing member for angular adjustment about the axis of rotation of said shaft, and reference marks on said rotor and said plate adapted to be aligned with each other at the instant said contact points are separated during said predetermined angular rotation of said shaft.

11. In apparatus of the class described, a casing member, a rotatable shaft journalled in said member, a plurality of circuit breakers adjustably mounted on said member, cam means mounted on said shaft for rotation therewith to periodically separate the contact points of each of said circuit breakers during predetermined angular movements of said shaft, a current distributing rotor mounted on said shaft for rotation therewith, a plate mounted on said member for angular adjustment about the axis of rotation of said shaft, a reference mark on said plate adapted to be aligned with a reference mark on said rotor at the instant the contact points of one of said circuit breakers are separated during a predetermined angular rotation of said shaft, and additional reference marks on said plate for use in conjunction with the reference mark on said rotor for properly adjusting the other of said circuit breakers relative to said one circuit breaker and said cam means for operating the same after said plate has been secured in position in proper relation with respect to said one circuit breaker.

12. In apparatus of the class described, a rotatable shaft, two circuit breakers mounted Ior adjustment relative to said shaft, cam means on said shaft for alternately periodically separating the contact points of said circuit breakers during the predetermined angular rotations of said shaft, a current distributing rotor mounted on said shaft for rotation therewith, a plate adapted for 15 1,891534 5 angular rotations of said shaft.

JAKOB R. FREI. ROLLAND MI. PURDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Carlstedt Dec. 20, 1932 2,257,781 Bohli Oct. '7, 1941 

